1. Technical Field
This Patent Document relates generally to providing galvanic isolation between functional blocks of an electrical system, such as isolating a high voltage/power side from low voltage electronics.
2. Related Art
Galvanic isolation is used to prevent current flow (direct conduction path) from high voltage/power side to low voltage components. An example is an isolated driver for a power switching transistor (IGBT or power MOSFET). The low voltage gate driver electronics needs to be galvanically isolated from the power switching transistor.
FIG. 1A illustrates an optocoupler (opto-isolator) that includes and input side LED, and an output side photo transistor. The input LED is driven by input current from transmit electronics.
FIG. 1B illustrates an alternate capacitor based isolator. Capacitor based or transformer based isolators require a dedicated supply. The isolation capacitors allow AC flow, but block direct current, coupling AC signals between circuits at different DC voltages.
Systems originally designed to use opto-based isolators are designed to drive an LED. Substituting capacitor based or transformer based isolators in such systems requires emulating LED input characteristics for compatibility.
While this Background information references an example isolated power switching application, the Disclosure provided in this Patent Document is not limited to such applications.